1. Field of the Invention
This invention relates to the field of portable, rotary vane vacuum pumps and more particularly to the field of such pumps for use in servicing air conditioning and refrigeration systems.
2. Discussion of the Background
Portable, rotary vane vacuum pumps are widely used in the servicing of air conditioning and refrigerant systems to draw down a relatively deep vacuum before the system is recharged. In a typical servicing procedure, the refrigerant of the system is first recovered and the unit opened to atmosphere for repairs. Thereafter and prior to recharging it, the air and any residual moisture much be pulled out of the system otherwise its performance will be adversely affected. More specifically, any air and moisture left in the system will interfere with the refrigerant's thermal cycle causing erratic and inefficient performance. Additionally, any residual air and moisture can cause undesirable chemical reactions within the system components and form ice crystals within the system contributing to accelerated component failures.
The optimum operation of the vacuum pump used in such servicing is very important in order to draw as deep a vacuum as possible. Chief among the factors affecting its efficiency is the condition of the lubricating and sealing oil. Good service practices and most vacuum pump manuals call for the vacuum pump oil to be changed with every use. This frequent changing of the oil is recommended as it will quickly becomes laden with residual contaminants from the system and atmospheric moisture. These in turn lead to the inability of the vacuum pump to achieve a proper depth of vacuum to adequately pull air and moisture out of the system prior to recharging it.
In the field, the vacuum pump oil is rarely changed in the prescribed intervals or even when desirable because of the task's inherent mess and inconvenience. In most designs, the pump is submerged or at least partly submerged in an oil bath or sump for lubrication, sealing, and heat dissipation purposes. To change the oil, the sump must then be gravity drained or flushed and fresh oil poured into it. This can be a very time consuming and labor intensive procedure.
As an alternative to changing the oil for each use or at timed intervals, many pumps are commonly provided with a sight glass to allow the operator to view the level of the oil in the sump and monitor its condition. However, the sight glass in most cases becomes fouled and darken over time by a film of used oil making the viewing through it very difficult if not impossible. Consequently, the operator is really not able to truly monitor the level of the oil in the sump or its condition to decide if any servicing is needed.
With this and other problems in mind, the present invention was developed. In it, a rotary vane pump is disclosed that can draw a deep vacuum even with a single stage. Additionally, the pump is provided with a removable oil reservoir cartridge wherein the oil for the pump can be easily and quickly changed by simply removing and replacing the cartridge.